1. Field of the Invention
The present invention relates to image data processing.
2. Description of Prior Art
In a color image processing apparatus, a document is scanned for reading its image, and the obtained image data are converted to density data. Then, they are is subjected to various corrections. Before starting the scan, preprocessing is performed based on a prescan. For example, in the preprocessing, automatic exposure for removing the background of a document is performed, it is decided automatically whether the document is a color document or a monochromatic document, and the document size is detected.
It is also known that an image processing apparatus such as a printer has a test print circuit for performing test print, besides an image processing circuit for a normal print mode. A service man or the like can adjust the image forming process by using the test print circuit.
As mentioned above, an image processing apparatus performs operations not performed at the same time, and for each of the operations, a dedicated or separate circuit and a random access memory are provided. For example, in the first prior art apparatus mentioned above, the prescan and the scan are performed successively. Therefore, for example, the automatic exposure, the automatic color selection, the document size detection and the like performed in the prescan are not performed at the same time as the image reading in the scan. On the other hand, in the second prior art apparatus mentioned above, the test print and the normal image forming are not performed at the same time. Therefore, the print circuit for test print and the image processing circuit for normal print are not used at the same time. Therefore, the circuit scale of an image processing apparatus becomes larger, and this is one of factors which increases its cost.